We find soft X-ray emission lines from the X-ray binary Swift J1858.6-0814 in data from XMM-Newton-RGS: N VII, O VII and O VIII, as well as notable residuals short of a detection at Ne IX and other higher ionisation transitions. These could be associated with the disc atmosphere, as in accretion disc corona sources, or with a wind, as has been detected in Swift J1858.6-0814 in emission lines at optical wavelengths. Indeed, the N VII line is redshifted, consistent with being the emitting component of a P-Cygni profile. We find that the emitting plasma has an ionisation parameter $\log(\xi)=1.35\pm0.2$ and a density $n>1.5\times10^{11}$ cm$^{-3}$. From this, we infer that the emitting plasma must be within $10^{13}$ cm of the ionising source, $\sim5\times10^{7}r_{\rm g}$ for a $1.4M_{\odot}$ neutron star, and from the line width that it is at least $10^4r_{\rm g}$ away ($2\times10^{9}(M/1.4M_{\odot})$ cm). We compare this with known classes of emission line regions in other X-ray binaries and active galactic nuclei.

中文翻译：

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使用 XMM-牛顿反射光栅光谱仪观察到的 X 射线双星 Swift J1858.6-0814 中的软 X 射线发射线：圆盘大气还是风？

我们在 XMM-Newton-RGS 的数据中发现了来自 X 射线双星 Swift J1858.6-0814 的软 X 射线发射线：N VII、O VII 和 O VIII，以及在 Ne IX 处未检测到的显着残差和其他更高的电离跃迁。这些可能与盘状大气有关，如吸积盘日冕源，或与风有关，如在 Swift J1858.6-0814 中在光波长的发射线中检测到的那样。事实上，N VII 线是红移的，与 P-Cygni 剖面的发射成分一致。我们发现发射等离子体具有电离参数 $\log(\xi)=1.35\pm0.2$ 和密度 $n>1.5\times10^{11}$ cm$^{-3}$。由此，我们推断发射等离子体必须在离电离源 $\sim5\times10^{7}r_{\rm g}$ 的 $10^{13}$ cm 内，对于 $1.4M_{\odot}$ 中子星星，从线宽来看，它至少有 $10^4r_{\rm g}$ 远（$2\times10^{9}(M/1.4M_{\odot})$ cm）。我们将其与其他 X 射线双星和活动星系核中已知类别的发射线区域进行比较。